Because carbon dioxide (CO2) is the most significant greenhouse gas, technologies for sequestration and reducing carbon dioxide through capture, storage, conversion, etc. are actively being proposed. Among them, the GTL (gas to liquids) process is drawing attentions as an important technology for providing hydrocarbons obtained from petroleum resources with the recent development of shale gas.
The Fischer-Tropsch (FT) synthesis process, a critical process in the GTL technology, is a process whereby hydrocarbons are produced from a synthesis gas produced through reforming of natural gas. However, additional separation and upgrading processes are necessary because the hydrocarbons produced through the FT synthesis process are various in the number of carbon atoms. Therefore, for simplification of the GTL process and effective hydrocarbon production, studies are actively being conducted on the synthesis of hydrocarbons with a relatively narrow carbon number range by optimizing the condition of the FT synthesis process.
In the FT synthesis process, iron-based catalysts and cobalt-based catalysts are mainly used. Although iron-based catalysts were used mainly in the early stage of development, cobalt-based catalysts are mainly used recently. However, because the synthesis gas which is used as a source material in the FT synthesis process using cobalt-based catalysts should have a H2/CO molar ratio close to 2, it is difficult to satisfy the operating condition. In addition, because the use of carbon dioxide contained in the synthesis gas is not considered, both thermal and carbon efficiency for the overall process are relatively low and secondary environmental problems may occur. In contrast, the FT synthesis process using iron-based catalysts is an environment-friendly process with relatively high thermal efficiency and carbon efficiency because carbon dioxide can be converted to hydrocarbons by water gas shift reaction [see patent document 1].
Monocyclic aromatic compounds such as benzene, toluene, xylene, ethylbenzene, etc. or olefin compounds are used as source materials for petrochemicals such as synthetic fibers, plastics, gasoline additives, etc. In the existing methods, monocyclic aromatic compounds or olefin compounds are produced mainly from mixed fuel oil.
As the methods for preparing monocyclic aromatic compounds, patent documents 2-5 propose preparation from polycyclic aromatic compounds contained in light cycle oil (LCO), etc. using zeolite catalysts. However, the methods proposed in the patent documents 2-5 have the problems that the yield of monocyclic aromatic compounds is not high and the catalyst is easily deactivated during the reaction due to carbon deposition.
As the methods for preparing olefin compounds, patent documents 6-8 propose preparation of light olefins such as ethylene, propylene, etc. from naphtha or heavy hydrocarbons using zeolite catalysts. However, the preparation of long-chain olefin compounds with 6-17 carbon atoms is not described at all in the patent documents 6-8.